Conventionally, in the design operations of various kinds of apparatuses, the function of each design target has been studied under various conditions before the actual fabrication of a product by performing various kinds of simulations using an information processing apparatus (to be sometimes referred to as a computer), thereby reducing the number of steps and development period and cost required to manufacture and test a prototype.
As such a design support system, in the field of office equipment and computer peripheral equipment including copying machines, LBPs (Laser Beam Printers), and the like, there has been proposed a technique of simulating the behavior of a sheet-like flexible medium such as a recording sheet or film to be conveyed through a convey path as a design target constituted by mechanical components such as convey guides and convey rollers when the flexible medium is conveyed in the convey path.
A technique of increasing the calculation speed of a computer by simply expressing a flexible medium by masses and linear springs has been proposed in a paper contributed to the Japan Society of Mechanical Engineers. According to this paper, an elastic body representation of the tensile stiffness of the flexible medium is realized by connecting mass points with translational springs with a linear characteristic, and that of the flexural stiffness is realized by connecting mass points with rotational springs with a linear characteristic.
Numerical calculation (numerical analysis) of the motion (behavior) of a flexible medium by an information processing apparatus can be solved by establishing the motion equation of the flexible medium discretely expressed by finite elements or mass-spring systems in the above manner, and in an analysis target time (interval) divided into unit time steps each having a finite width, executing numerical time integration to sequentially obtain unknown accelerations, velocities, and displacements in the respective unit time steps starting from time 0. As such sequences, the Newmark-β method, Wilson-θ method, Euler's method, Kutta-merson method, and the like are widely known.
Assume that a design/analysis support system based on the above conventional analysis technique for a flexible medium convey path is to make analysis for a case wherein a plurality of different kinds of flexible media are conveyed in a convey path as a design target, and a flexible medium whose obverse and reverse surfaces have different stiffness against flexural deformation, for example, coated paper having a coated layer formed on only one surface or plain paper having a toner layer formed on one surface, is conveyed. In this case, since such a flexible medium exhibits different stiffness against flexural deformation (flexural stiffness) in different bending directions, the behavior of the flexible medium cannot be faithfully expressed by simply replacing the flexural stiffness with rotational springs.
In addition, in creating a model of a flexible medium or displaying a calculation result, it is difficult to discriminate which side of the flexible medium is a coated layer or toner layer.